/*
 * Copyright (c) 2014 Cesanta Software Limited
 * All rights reserved
 */

#ifndef MJS_GC_H_
#define MJS_GC_H_

#include "mjs_core.h"
#include "mjs_mm.h"
#include "mjs_internal.h"

#if defined(__cplusplus)
extern "C" {
#endif /* __cplusplus */

/*
 * performs arithmetics on gc_cell pointers as if they were arena->cell_size
 * bytes wide
 */
#define GC_CELL_OP(arena, cell, op, arg) \
  ((struct gc_cell *) (((char *) (cell)) op((arg) * (arena)->cell_size)))

struct gc_cell {
  union {
    struct gc_cell *link;
    uintptr_t word;
  } head;
};

/*
 * Perform garbage collection.
 * Pass true to full in order to reclaim unused heap back to the OS.
 */
void mjs_gc(struct mjs *mjs, int full);

MJS_PRIVATE int gc_strings_is_gc_needed(struct mjs *mjs);

/* perform gc if not inhibited */
MJS_PRIVATE int maybe_gc(struct mjs *mjs);

MJS_PRIVATE struct mjs_object *new_object(struct mjs *);
MJS_PRIVATE struct mjs_property *new_property(struct mjs *);
MJS_PRIVATE struct mjs_ffi_sig *new_ffi_sig(struct mjs *mjs);

MJS_PRIVATE void gc_mark(struct mjs *mjs, mjs_val_t *val);

MJS_PRIVATE void gc_arena_init(struct gc_arena *, size_t, size_t, size_t);
MJS_PRIVATE void gc_arena_destroy(struct mjs *, struct gc_arena *a);
MJS_PRIVATE void gc_sweep(struct mjs *, struct gc_arena *, size_t);
MJS_PRIVATE void *gc_alloc_cell(struct mjs *, struct gc_arena *);

MJS_PRIVATE uint64_t gc_string_mjs_val_to_offset(mjs_val_t v);

/* return 0 if v is an object/function with a bad pointer */
MJS_PRIVATE int gc_check_val(struct mjs *mjs, mjs_val_t v);

/* checks whether a pointer is within the ranges of an arena */
MJS_PRIVATE int gc_check_ptr(const struct gc_arena *a, const void *p);

#if defined(__cplusplus)
}
#endif /* __cplusplus */

#endif /* MJS_GC_H_ */
